Trump’s proposal to ship undocumented immigrants to Mexico to await their immigration hearings -- assuming the country would take them -- is vulnerable to attack, Hincapie said. Deporting people before they’ve had a hearing, or been ordered out of the country by a judge, “raises a whole host of constitutional violations,” she said.
https://www.bloomberg.com/politics/articles/2017-02-22/trump-s-immigration-crackdown-likely-to-bring-lawsuit-flood